The invention relates to elastic drive assemblies or rotary parts (hereinafter called sheaves) which can be used as pulleys or sprocket wheels to transmit motion to endless flexible members in the form of belts, ropes or chains. More particularly, the invention relates to improvements in sheaves which can be utilized with advantage in motor vehicles to transmit motion from the output shaft (,e.g., crankshaft) of an internal combustion engine to one or more auxiliary aggregates including fans, pumps, air conditioners and/or others.
It is known to provide a sheave with an input element which is affixed to the shaft of an engine or another prime mover, an output element which is coaxial with and is rotatable relative to the input element and is provided with or carries a rim serving to be engaged by one or more endless belts or chains, and a damping unit which is installed between and opposes rotation of the input and output elements relative to each other, The damping unit comprises springs which are designed and installed to store energy in response to rotation of the input and output elements relative to each other. The sheave further comprises a bearing which is installed between the input and output elements. A so-called inertial damper serves to damp vibrations of the input and output elements.